EP4026651A1 - Dispositif d'inspection de qualité de soudure - Google Patents

Dispositif d'inspection de qualité de soudure Download PDF

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Publication number
EP4026651A1
EP4026651A1 EP21765449.0A EP21765449A EP4026651A1 EP 4026651 A1 EP4026651 A1 EP 4026651A1 EP 21765449 A EP21765449 A EP 21765449A EP 4026651 A1 EP4026651 A1 EP 4026651A1
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EP
European Patent Office
Prior art keywords
welded portion
resistance
holes
resistance value
cradle
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP21765449.0A
Other languages
German (de)
English (en)
Other versions
EP4026651B1 (fr
EP4026651A4 (fr
Inventor
Jung Hoon Lee
Su Taek Jung
Seok Jin Kim
Ji Hoon Lee
Sang Hyun Koo
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LG Energy Solution Ltd
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LG Energy Solution Ltd
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Filing date
Publication date
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Publication of EP4026651A1 publication Critical patent/EP4026651A1/fr
Publication of EP4026651A4 publication Critical patent/EP4026651A4/fr
Application granted granted Critical
Publication of EP4026651B1 publication Critical patent/EP4026651B1/fr
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Anticipated expiration legal-status Critical

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K31/00—Processes relevant to this subclass, specially adapted for particular articles or purposes, but not covered by only one of the preceding main groups
    • B23K31/12—Processes relevant to this subclass, specially adapted for particular articles or purposes, but not covered by only one of the preceding main groups relating to investigating the properties, e.g. the weldability, of materials
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/20—Investigating the presence of flaws
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K31/00—Processes relevant to this subclass, specially adapted for particular articles or purposes, but not covered by only one of the preceding main groups
    • B23K31/12—Processes relevant to this subclass, specially adapted for particular articles or purposes, but not covered by only one of the preceding main groups relating to investigating the properties, e.g. the weldability, of materials
    • B23K31/125—Weld quality monitoring
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/041—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/20—Metals
    • G01N33/207—Welded or soldered joints; Solderability
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4285—Testing apparatus
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/48—Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/536—Electrode connections inside a battery casing characterised by the method of fixing the leads to the electrodes, e.g. by welding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K2101/00—Articles made by soldering, welding or cutting
    • B23K2101/36—Electric or electronic devices
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to an apparatus for inspecting a welding state in a welded portion for an electronic or mechanical coupling in a lithium secondary battery, and more particularly, to an apparatus for inspecting whether a weak welding was performed on a welded portion between an electrode tab and an electrode tab and a welded portion between an electrode tab and an electrode lead.
  • a secondary battery unlike a primary battery that cannot be charged, means a battery that can be charged and discharged, and is widely used in electronic devices such as mobile phones, notebook computers, camcorders, or electric vehicles.
  • the lithium secondary battery has a larger capacity than a nickel-cadmium battery or a nickel-hydrogen battery, and because the energy density per unit weight is high, the degree of utilization thereof is rapidly increasing.
  • lithium secondary batteries are classified according to the structure of the electrode assembly having a positive electrode/separator/negative electrode structure.
  • Representative examples thereof include a jelly-roll electrode assembly in which long sheet type positive electrodes and negative electrodes are wound with a separator interposed therebetween, a stacked electrode assembly in which a plurality of positive and negative electrodes cut in a predetermined size unit are sequentially stacked with a separator interposed therebetween, and a stacked/foldable electrode assembly in which bi-cells or full cells, in which positive and negative electrodes of a predetermined unit are stacked with a separator interposed therebetween, are wound.
  • a pouch type battery having a stack type or stack/folding type electrode assembly embedded in a pouch-shaped battery case made of an aluminum laminate sheet has attracted a lot of attention due to its low manufacturing cost and small weight, and the amount used thereof is gradually increasing.
  • the lithium secondary battery mainly uses a lithium-based oxide and a carbon material as a positive electrode active material and a negative electrode active material, respectively.
  • the lithium secondary battery includes an electrode assembly, in which a positive electrode plate and a negative electrode plate coated with the positive electrode active material and the negative electrode active material, respectively, are disposed with a separator disposed therebetween, and an exterior material that seals and stores the electrode assembly together with the electrolyte.
  • a plurality of positive electrode tabs which are extended from a plurality of positive electrode plates, and a plurality of negative electrode tabs, which are extended from a plurality of negative electrode plates, are formed in the electrode assembly, and the plurality of positive electrode tabs and the plurality of negative electrode tabs are respectively coupled with the positive electrode lead and the negative electrode lead by welding.
  • a plurality of positive electrode tabs and a plurality of negative electrode tabs form an electrode tab
  • a positive electrode lead and a negative electrode lead form an electrode lead.
  • an object of the present invention is to provide an apparatus for inspecting a weak welding of a welded portion with excellent detection power while allowing complete enumeration.
  • a welding state inspection apparatus of the present invention for achieving the above purposes is an apparatus for inspecting a welding state in a welded portion for an electronic or mechanical coupling in a lithium secondary battery, the apparatus including: a measuring unit configured to obtain data for deriving a resistance value of the welded portion by allowing a resistance measuring probe to contact the welded portion; and a controller configured to communicate with the measuring unit, determine the resistance value of the welded portion by receiving the data obtained from the measuring unit, and determine whether a weak welding was performed by comparing the determined resistance value with a threshold resistance value, wherein the measuring unit is configured to allow the resistance measuring probe to contact one end and the other end of the welded portion.
  • the controller determines that a weak welding was performed if the determined resistance value exceeds the threshold resistance value.
  • the measuring unit includes: a flat cradle on which a subject is mounted; an upper plate configured to be positioned on an upper portion having a predetermined separation distance from the cradle and include a plurality of through holes into which the resistance measuring probe is insertable; a lower plate configured to be positioned on a lower portion having a predetermined separation distance from the cradle and include a plurality of through holes into which the resistance measuring probe is insertable; a coupling unit configured to allow the cradle, the upper plate and the lower plate to be coupled to each other; and a pair of resistance measuring probes configured to obtain data for determining a resistance value by contacting the welded portion.
  • one resistance measuring probe includes a current probe and a voltage probe.
  • an upper guide member and a lower guide member for allowing the resistance measuring probe to be inserted into a correct position are coupled to the upper plate and the lower plate, respectively.
  • the upper guide member and the lower guide member have through holes into which the resistance measuring probe is insertable, respectively, the through holes of the upper guide member and the through holes of the upper plate are located on a straight line to thereby allow the resistance measuring probe to pass the through holes to approach an upper surface of the welded portion, and the through holes of the lower guide member and the through holes of the lower plate are located on a straight line to thereby allow the resistance measuring probe to pass the through holes to approach a lower surface of the welded portion.
  • the coupling unit includes a coupling bar and a coupling screw.
  • the cradle, the upper plate and the lower plate each has coupling holes at 4 edge portions, and the upper plate, the cradle and the lower plate are coupled as the coupling bar sequentially passes through coupling holes formed on the upper plate, the cradle and the lower plate.
  • the apparatus further includes a compression spring for adjusting a separation distance between the cradle and the upper plate and a separation distance between the cradle and the lower plate, wherein the coupling bar is configured to be insertable into a hollow portion of the compression spring.
  • the controller includes a threshold resistance value setting program for setting the threshold resistance value by processing data obtained for a sample group by a statistical scheme.
  • resistance values determined from data obtained for the sample group form a normal distribution curve.
  • the inspection apparatus of the present invention further includes an output unit configured to display data obtained from the measuring unit and resistance values of the welded portion determined by the controller.
  • the inspection apparatus of the present invention further includes a power source configured to apply power to the measuring unit, wherein the power is a direct current (DC) power and is controlled by the controller.
  • a power source configured to apply power to the measuring unit, wherein the power is a direct current (DC) power and is controlled by the controller.
  • DC direct current
  • welded state inspection method of the present invention resistances of a sample group are measured, a threshold resistance value is set from a normal distribution curve of the measured resistance values, and microresistances having a resolution of nanoohm to microohm levels can be measured when measuring resistances for the sample group and the welded portion to be inspected, thereby showing an excellent detection power for a weak welding defect.
  • the present invention provides an apparatus for inspecting a welding state in a welded portion for an electronic or mechanical coupling in a lithium secondary battery, the apparatus including: a measuring unit configured to obtain data for deriving a resistance value of the welded portion by allowing a resistance measuring probe to contact the welded portion; and a controller configured to communicate with the measuring unit, determine the resistance value of the welded portion by receiving the data obtained from the measuring unit, and determine whether a weak welding was performed by comparing the determined resistance value with a threshold resistance value, in which the measuring unit is configured to allow the resistance measuring probe to contact one end and the other end of the welded portion.
  • FIG. 6 is a schematic diagram of a resistance measuring probe according to an embodiment of the present invention.
  • a pair of resistance measuring probes 150 and 150' of the present invention are provided, which include a pair of current probes and a pair of voltage probes.
  • one resistance measuring probe 150 includes a current probe 151 and a voltage probe 152
  • another resistance measuring probe 150' also includes a current probe 151' and a voltage probe 152'.
  • the resistance of the welded portion can be measured by a 4-wire type measuring scheme.
  • the current probe applies current to a welded portion to be measured, and the voltage probe measures voltages. As such, the resistance of the welded portion can be determined.
  • data for determining the resistance value is obtained by allowing a pair of resistance measuring probes to contact the welded portion.
  • the resistance of the welded portion can be measured by a 4-wire type measuring scheme. Since the 4-wire type resistance measuring scheme is less influenced by the contact resistance compared to the 2-wire type resistance measuring scheme, the microresistance can be more precisely measured in the 4-wire type resistance measuring scheme, in which the resistance can be measured even in nanoohm units.
  • FIG. 1 is a schematic diagram of a measuring unit 100 constituting the welding state inspection apparatus according to an embodiment of the present invention.
  • the measuring unit 100 of the present invention includes: a flat cradle 110 on which a subject is mounted; an upper plate 120 configured to be positioned on an upper portion having a predetermined separation distance from the cradle and include a plurality of through holes into which the resistance measuring probe is insertable; a lower plate 130 configured to be positioned on a lower portion having a predetermined separation distance from the cradle and include a plurality of through holes into which the resistance measuring probe is insertable; a coupling unit 140 configured to allow the cradle, the upper plate and the lower plate to be coupled to each other; and a pair of resistance measuring probes 150 and 150' configured to obtain data for determining a resistance value by contacting the welded portion.
  • the cradle 110 is a flat rectangular member on which a subject including a welded portion to be inspected is placed, and the subject is mounted on the central portion.
  • FIG. 2 is a plan view of a cradle 110 according to an embodiment of the present invention.
  • the cradle 110 of the present invention includes a plurality of coupling holes 111 into which the coupling bar to be described later can be inserted, and the coupling holes are formed at 4 edge portions of the cradle.
  • a rectangular through hole 112 is formed on a portion corresponding to the welded portion of the subject in a thickness direction of the cradle to allow the resistance measuring probe to contact the top and backside of the welded portion, and the welded portion is positioned in the through hole 112 region.
  • the upper plate 120 is positioned at a position having a predetermined separation distance in a vertical upper direction from the cradle 110.
  • the upper plate is flat like the cradle and includes a plurality of through holes into which the resistance measuring probe including a current probe and a voltage probe can be inserted.
  • FIG. 3 is a plan view of the upper plate 120 according to one embodiment.
  • the upper plate of the present invention is a flat rectangular member and has coupling holes 121 at 4 edge portions, respectively. Further, the coupling bars (not shown) to be described later are inserted into the coupling holes.
  • the upper plate 120 includes through holes 122 into which the resistance measuring probe can be inserted.
  • a plurality of through holes are formed at portions corresponding to one end and the other end of the welded portion.
  • the resistance measuring probe can approach one end and the other end of the welded portion. Further, the resistance measuring probe, which is inserted into the upper plate, can approach the top of the welded portion.
  • the lower plate 130 is positioned at a position having a predetermined separation distance in a vertical lower direction from the cradle 110.
  • the lower plate is a flat rectangular member and has a plurality of through holes in which the resistance measuring probe can be inserted like the upper plate. 4 edge portions of the lower plate have coupling holes, respectively, and the coupling bars to be described later are inserted into the coupling holes.
  • the lower plate has a plurality of through holes, into which the resistance measuring probe can be inserted, as in the upper plate, and the through holes may be formed on portions corresponding to one end and the other end of the welded portions. As such, the resistance measuring probe can approach one end and the other end of the welded portion. Further, the resistance measuring probe, which is inserted into the lower plate, can approach the backside of the welded portion.
  • the inserted location of the resistance measuring probe can be appropriately adjusted according to the inspected location of the welded portion.
  • the upper guide member 160 and the lower guide member are coupled with the upper plate 120 and the lower surface 130, respectively.
  • the upper guide member 160 and the lower guide member allow the resistance measuring probe to be inserted at a correct position.
  • FIG. 4 is a coupling diagram of an upper plate and an upper guide member according to an embodiment of the present invention.
  • the upper guide member 160 includes a plurality of through holes 161 into which the resistance measuring probe can be inserted.
  • there are two through holes and the resistance measuring probe can be inserted into each of the through holes.
  • the through holes are formed on portions corresponding to one end and the other end of the welded portion.
  • the resistance measuring probe can be inserted into both one end and the other end of the welded portion, or the resistance measuring probe can also be inserted into only one of one end and the other end of the welded portion.
  • the upper plate 120 has a plurality of through holes 122.
  • the resistance measuring probe 150 sequentially passes through the through hole 161 of the upper guide member 160 and the through holes 122 of the upper plate 120, to thereby approach the upper surface of the welded portion of the subject.
  • the through holes are placed on a straight line in a direction in which the resistance measuring probe is inserted as in FIG. 4 .
  • the upper guide member 160 allows the resistance measuring probe to be inserted in the thickness direction of the upper plate in a non-inclined state and fixes the resistance measuring probe.
  • the lower guide member is coupled with the lower plate, and the lower guide member includes a plurality of through holes into which the resistance measuring probe can be inserted, as in the upper guide member. Further, there may be two through holes, and the resistance measuring probe may be inserted into each of the through holes.
  • the lower plate includes through holes as in the upper plate, and the resistance measuring probe sequentially the through hole of the lower guide member and the through hole of the lower plate, to thereby approach the lower surface of the welded portion of the subject on the cradle.
  • the through hole of the lower guide member and its corresponding through hole of the lower plate are placed on a straight line in a direction in which the resistance measuring probe is inserted.
  • Such a lower guide member fixes the resistance measuring probe while allowing the resistance measuring probe to be inserted in a non-inclined manner as in the upper guide member.
  • the cradle, the upper plate and the lower plate constituting the measuring unit of the present invention are coupled by the coupling unit.
  • the cradle, the upper plate and the lower plate include coupling holes at 4 edge portions, and the coupling unit includes a coupling bar and coupling screws.
  • the coupling unit 140 of the present invention is configured to allow the coupling bar 141 to pass through the coupling holes of the upper plate 120, the cradle 110 and the lower plate 130 to be inserted, to thereby allow the upper plate, the cradle and the lower plate to be coupled with each other.
  • the measuring unit 100 of the present invention further includes a compression spring 170 for adjusting a separation distance between the cradle 110 and the upper plate 120 and a separation distance between the cradle 110 and the lower plate 130, and the coupling bar 141 can be inserted into the hollow portion of the compression spring 170.
  • the upper plate 120 and the lower plate 130 may respectively move along the coupling bar 141 in a vertical direction by elasticity of the compression spring 170.
  • the upper plate 120 and/or the lower plate 130 may be positioned at desired positions and they may then fixed at desired positions by using coupling screws 142.
  • the compression spring 170 may have a length of a distance from the upper plate to the lower plate corresponding to one coupling bar 141, but one coupling bar 141 may pass through two compression springs.
  • one compression spring has a length corresponding to the length between the upper plate 120 and the cradle 110
  • another compression spring has a length corresponding to the length between the lower plate 130 and the cradle 110.
  • the welding state inspection apparatus of the present invention further includes an output unit configured to display data obtained from the measuring unit and resistance values of the welded portion determined by the controller.
  • the inspection performer can check the resistance value of the welded portion to be inspected through the output unit.
  • the welding state inspection apparatus of the present invention further includes a power source for applying power to the measuring unit.
  • the power is preferably DC power. This is because the direct current scheme has an advantage that high-precision resistance measurement is possible, compared to the alternating current scheme.
  • the controller controls the size of the current applied to the measuring unit, the current application time, and the point of time of applying the current, etc.
  • the controller of the present invention communicates with the measuring unit, determines the resistance value of the welded portion by receiving the data obtained from the measuring unit, and determines whether a weak welding was performed by comparing the determined resistance value with a threshold resistance value.
  • the controller includes a threshold resistance value setting program for setting the threshold resistance value by processing data obtained for a sample group by a statistical scheme.
  • the inventors of the present invention have found that the electric resistance value of the welded portion having a low welding strength was greater than the electric resistance value of the welded portion having a normal welding strength, which has led them to the present invention.
  • a resistance value of a welded portion having been welded by a normal welding strength of 22 kgf or more is smaller than a resistance value of a welded portion having been welded by a weak welding strength less than 22 kgf.
  • a separate process of measuring the tensile strength of the welded portion was necessary because the correlation between the tensile strength of the welded portion and the resistance was used when deriving the threshold resistance value.
  • the inspection apparatus of the present invention does not rely on the correlation between the resistance and the tensile strength of the welded portion and uses a statistical scheme in deriving a threshold resistance value, and precisely measures the resistance by measuring the resistance up to nanoohm to microohm units by increasing the resolution in obtaining data for determining the resistance value of the welded portion.
  • resistance values form a normal distribution curve from data obtained for a large amount of sample groups.
  • an object having a large deviation may be easily assumed as being defective from a standpoint of a statistical probability, and thus a predetermined deviation is determined as a threshold resistance value.
  • this approach is based on a premise that data for the sample group are reliable.
  • a measuring unit of the present invention capable of precisely measuring the resistance up to nanoohm to microohm levels for the sample group is used in the process of setting a threshold resistance value, and a measuring unit of the present invention capable of precisely measuring the resistance up to nanoohm to microresistance levels is used when measuring the resistance for the object to be inspected.
  • the controller constituting the inspection apparatus of the present invention includes a program for setting a threshold resistance value by processing data obtained by the measuring unit for a sample group by a statistical scheme. As such, there is no need for separately measuring the tensile strength of the welded portion in order to set the threshold resistance value unlike the conventional technology.
  • a method for inspecting a welding defect includes: a threshold resistance setting step (S100) of measuring a resistance of a welded portion of a sample group and deriving a threshold resistance value which becomes an evaluation standard of a weak welding; a resistance measuring step (S200) of measuring a resistance value of a welded portion to be inspected; and a determination step (S300) of determining as a weak welding if the resistance value measured in the resistance measuring step exceeds the threshold resistance value, wherein the threshold resistance setting step (S100) and the resistance measuring step (S200) uses the above-described measuring unit.
  • the threshold resistance setting step (S100) includes: a data construction step (S110) for determining the resistance value of a welded portion of a sample group and storing the determined resistance value; and a threshold resistance value deriving step (S120) for deriving the threshold resistance value by processing data accumulated by the data construction step (S110) by a statistical scheme.
  • the data construction step (S110) includes the process of obtaining data for determining the resistance of the welded portion for a large amount of objects constituting a sample group by using the measuring unit constituting the inspection apparatus of the present invention, and determining the resistance value based on the obtained data.
  • a pair of resistance measuring probes constituting the measuring unit of the present invention are allowed to contact the welded portion.
  • one resistance measuring probe includes a current probe and a voltage probe
  • a pair of resistance measuring probes include a pair of current probes and a pair of voltage probes.
  • 4-wire type resistance measurement is possible.
  • the 4-wire type resistance measuring scheme has an advantage of being capable of more precisely obtaining data due to a small contact resistance, compared to the 2-wire type resistance measuring scheme.
  • the number of objects of the sample group is at least 100,000, preferably 200,000, and it is preferable to have as many objects of the sample group as possible in terms of reliability.
  • the threshold resistance value deriving step (S120) includes deriving a threshold resistance value by processing data accumulated by the data construction step (S110) by a statistical scheme.
  • the controller constituting the inspection apparatus of the present invention includes a program for setting a threshold resistance value by processing data by a statistical scheme.
  • the program may obtain a normal distribution curve of individual resistance values held by objects of the sample group, and in the normal distribution curve, a sum of a standard deviation and an average value of the individual resistance values may be set as the threshold resistance value.
  • the probability that an object having a deviation of 1 ⁇ (standard deviation) appears is about 32%
  • the probability that an object having a deviation of 28 appears is about 5%
  • the probability that an object having a deviation of 38 appears is about 0.3%
  • the probability that an object having a deviation of 4 ⁇ appears is about 0.01%
  • the probability that an object having a deviation of 5 ⁇ appears is about 0.001%
  • the probability that an object having a deviation of 6 ⁇ appears is about 0.0000001%. Therefore, even if the sum of the average value and 6 ⁇ is set as the threshold resistance value and it is assumed the resistance value greater than the sum indicates that a weak welding has been performed, the reliability is very high.
  • the resistance measuring step (S200) includes obtaining data for determining the resistance value of the welded portion to be inspected by the measuring unit constituting the inspection apparatus of the present invention.
  • the measuring unit of the present invention includes two resistance measuring probes and obtains data for deriving the resistance value by allowing the two resistance measuring probes to contact the welded portion.
  • FIG. 8 is a schematic diagram showing a process of acquiring data using a resistance measuring probe according to one embodiment of the present invention. Referring to FIG. 8 , one resistance measuring probe 150 is allowed to contact one end 31 of the welded portion 30, and the remaining one resistance measuring probe 150' is allowed to contact the other end 32 of the welded portion 30, to thereby measure the entire resistance of the welded portion 30. Further, according to the embodiment of FIG. 8 , two resistance measuring probes 150 and 150' are positioned on the upper surface of the welded portion. As illustrated in FIG.
  • the welded portion 30 can be divided into a welded portion 33 of the electrode tab 20 portion and a welded portion 34 of the electrode lead 10, and both of the two resistance measuring probes can be allowed to contact the welded portion 33 of the electrode tab. Alternatively, all of the two resistance measuring probes can be allowed to contact the welded portion 34 of the electrode lead portion.
  • FIG. 9 is a schematic diagram showing a process of acquiring data using a resistance measuring probe according to another embodiment of the present invention.
  • one resistance measuring probe 150 may be allowed to contact the welded portion 33 of the electrode tab portion, and the remaining one resistance measuring probe 150' may be allowed to contact the welded portion of the electrode lead portion, to thereby perform resistance measurement.
  • the welding state inspection apparatus and welding defect inspection method of the present invention can be widely applied to the welded portion of the secondary battery and can be applied to the welded portion according to various welding schemes. Namely, the welding defect inspection method of the present invention can be applied to a welded portion between an electrode tab and an electrode tab, a welded portion between an electrode tab and an electrode lead, and a welded portion between an electrode lead and a bus bar in a battery pack, and may also be applied to a welded portion by ultrasonic welding and a welded portion by laser welding, etc.
  • resistances of a sample group are measured, a threshold resistance value is set from a normal distribution curve of the measured resistance values, and resistances are precisely measured by using a microresistance measuring instrument having a resolution of nanoohm to microohm levels when measuring resistances for the sample group and the welded portion to be inspected, thereby showing an excellent detection power for a weak welding defect.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Physics & Mathematics (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
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  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Food Science & Technology (AREA)
  • Medicinal Chemistry (AREA)
  • Quality & Reliability (AREA)
  • Measurement Of Resistance Or Impedance (AREA)
  • Connection Of Batteries Or Terminals (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
  • Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
  • Testing Electric Properties And Detecting Electric Faults (AREA)
  • Secondary Cells (AREA)
EP21765449.0A 2020-03-02 2021-02-08 Dispositif d'inspection de qualité de soudure Active EP4026651B1 (fr)

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KR1020200026135A KR20210111076A (ko) 2020-03-02 2020-03-02 용접 상태 검사 장치
PCT/KR2021/001653 WO2021177613A1 (fr) 2020-03-02 2021-02-08 Dispositif d'inspection de qualité de soudure

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CN (1) CN114556093A (fr)
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US20230251220A1 (en) * 2022-02-09 2023-08-10 United States Department Of Energy Apparatus and Method for Crack Measurement

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US20220373493A1 (en) 2022-11-24
PL4026651T3 (pl) 2024-07-29
CN114556093A (zh) 2022-05-27
JP2022552384A (ja) 2022-12-15
EP4026651B1 (fr) 2024-03-27
JP7540840B2 (ja) 2024-08-27
KR20210111076A (ko) 2021-09-10
EP4026651A4 (fr) 2022-09-28
ES2977964T3 (es) 2024-09-03
WO2021177613A1 (fr) 2021-09-10

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